The semi-hermetic scroll compressors, vacuum pumps, and expanders relate generally to devices that alter or reduce the pressure of gases within a container, typically to very low vacuums. More specifically, these devices refer to internal housing fins and magnetic coupling usage that improve cooling and prevent the intrusion of atmospheric air within the housing and into the working fluid while the invention is strictly air cooled.
A unique aspect of the present invention is a closed housing for gases other than air that transfers heat from the housing without infiltration of gases into the housing during compression or expansion of the gas other than air within the housing.
Scroll devices have been used as compressors and vacuum pumps for many years. In general, they have been limited to a single stage of compression due to the complexity of two or more stages. In a single stage, a spiral involute or scroll upon a rotating plate orbits within a fixed spiral or scroll upon a stationery plate. A motor shaft turns a shaft that orbits a scroll eccentrically within a fixed scroll. The eccentric orbit forces a gas through and out of the fixed scroll thus creating a vacuum in a container in communication with the fixed scroll. An expander operates with the same principle only turning the scrolls in reverse. When referring to compressors, it is understood that expander or vacuum pump can be used.
Often oil is used during manufacture and operation of compressors. Oil free or oil less scroll type compressors and vacuum pumps have difficult and expensive manufacturing, due to the high precision of the scroll in each compressor and pump. For oil lubricated equipment, swing links often minimize the leakage from gaps in the scrolls by allowing the scrolls to contact the plate of the scroll. Such links cannot be used in an oil free piece of equipment because of the friction and wear upon the scrolls. If the fixed and orbiting scrolls in oil free equipment lack precision, leakage will occur and the equipment performance will decline as vacuums take longer to induce or do not arise at all.
Prior art designs have previously improved vacuum pumps, particularly the tips of the scrolls. In the preceding work of this inventor, U.S. Pat. No. 6,511,308, a sealant is applied to the scrolls during manufacturing. The pump with the sealant upon the scrolls is then operated which distributes the sealant between the scrolls. The pump is then disassembled to let the sealant cure. After curing the sealant, the pump is reassembled for use.
Then in U.S. Pat. No. 3,802,809 to Vulkliez, a pump has a scroll orbiting within a fixed scroll. Beneath the fixed disk, a bellows guides the gases evacuated from a container. The bellows spans between the involute and the housing, nearly the height of the pump. This pump and many others are cooled by ambient air in the vicinity of the pump.
In some applications, scroll type fluid displacement devices compress or expand gases other than air. Such applications include hydrogen recirculation pumps used in fuel cells, natural gas compressors used in micro-turbines, tritium vacuum pumps, Rankin cycle expanders, and the like. These applications call for a totally and completely enclosed housing so that the fluid undergoing compression or expansion does not leak from the housing into the nearby atmosphere or that the nearby atmosphere does not leak through the housing into the fluid undergoing compression or expansion. When compressing or expanding these fluids, heat arises in the various components of the present invention. The present invention though transfers heat from its fixed scroll and its orbiting scroll to the nearby atmosphere without leakage into the housing. Movement of the scrolls calls for transmission of power to the components of the invention also without leakage of the fluid undergoing compression or expansion.
The present art overcomes the limitations of the prior art where a need to exists for transmission of power and transfer of heat from a scroll fluid displacement device without leakage of a working fluid or infiltration of the atmosphere into the working fluid. That is, the art of the present invention, a semi-hermetic scroll device utilizes a magnetic coupling for power transfer and fins upon the orbiting scroll and inside the housing for heat transfer, both without leakage of the working fluid.